Magneto coil ring material..........?

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George Andreasen
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Magneto coil ring material..........?

Post by George Andreasen » Tue Mar 26, 2019 4:02 pm

Does anyone know what kind of material the magneto coil ring is made from? It looks like cast iron, or is it some kind of forging?


Joe Bell
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Re: Magneto coil ring material..........?

Post by Joe Bell » Tue Mar 26, 2019 5:22 pm

cast


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Re: Magneto coil ring material..........?

Post by Joe Bell » Tue Mar 26, 2019 5:22 pm

9-11 sheetmetal

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Mark Gregush
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Re: Magneto coil ring material..........?

Post by Mark Gregush » Tue Mar 26, 2019 7:28 pm

Ductile cast iron
"Difference Between Ductile Iron and Cast Iron. Ductile iron can be bent without breaking, whereas cast iron is brittle and breaks when bent. ... Ductile iron also consists of nodular graphite, which gives it flexibility. Cast iron mainly consists of carbon and silicon."
I know the voices aren't real but damn they have some good ideas! :roll:

1921 Huckster
1925 Cut down pickup


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George Andreasen
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Re: Magneto coil ring material..........?

Post by George Andreasen » Thu Mar 28, 2019 10:34 pm

THANK YOU MARK..................I had a feeling it might be something like ductile iron. I doubted that Henry would have been chinzy and used a simple casting. Cast won't bend. Ductile iron will.

Now, I asked for a very specific reason.....mine's bent, just enough that I won't be able to maintain proper clearance from the magnets at the bottom. I have the bolted side (top) fairly straight, but the unbolted end (at the bottom) needs to be pushed back out about .020" or so. I think I'll try and nudge it back gently with a hydraulic jack.


Les Schubert
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Re: Magneto coil ring material..........?

Post by Les Schubert » Thu Mar 28, 2019 10:40 pm

Interesting considering that “ductile iron” wasn’t invented until 1943!!


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George Andreasen
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Re: Magneto coil ring material..........?

Post by George Andreasen » Thu Mar 28, 2019 11:07 pm

True, but there was also "wrought iron". In any case, I'm trying to determine if I can safely "push" or bend the ring about .020".

It's kind of heartbreaking really........this is a rebuilt ring and looks beautiful. I'm sure the vendor ground everything perfectly flat, but since it was shipped in a cardboard box I'd be willing to bet a soggy doughnut that it got dropped somewhere along the shipping route. I just discovered it when trying to set up my magnet clearances.....got all kinds of goofy readings. I finally bolted an aluminum bar across the crankshaft flange and measured down to each coil face and found the error.

Since the ring got bent, it seems I should be able to push it back into position. I hope. Any other input?


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Re: Magneto coil ring material..........?

Post by Kohnke Rebabbitting » Fri Mar 29, 2019 1:16 am

George Andreasen wrote:
Thu Mar 28, 2019 10:34 pm
THANK YOU MARK..................I had a feeling it might be something like ductile iron. I doubted that Henry would have been chinzy and used a simple casting. Cast won't bend. Ductile iron will.

Now, I asked for a very specific reason.....mine's bent, just enough that I won't be able to maintain proper clearance from the magnets at the bottom. I have the bolted side (top) fairly straight, but the unbolted end (at the bottom) needs to be pushed back out about .020" or so. I think I'll try and nudge it back gently with a hydraulic jack.

George, I doubt if if your ring is bent. You are just not done shimming yet. If you haven't used .002, and .001 shims, you will never get it as level as it is possible to get. It does no good at all to surface a coil ring, as all the levelness comes in the form of shimming, and no other way.

The first thing you have to do is find the lowest magnet you have, on the flywheel. This is done by putting the flywheel, on the crank, and bolt it tight. We use the flywheel only, as the whole transmission is to much weight to mess with. With the coil ring bolted tight, revolve the flywheel over any coil spool on the top 1/2 of the motor, and measure the gap on all 16 magnet plates. The tightest one will be the lowest magnet plate, and your standard for measuring all gaps, and leveling your coil ring.

The next thing, you have to do, is get 9:00, and 3:00 to read as close as possible, as with in 2 to 3 thousandths, this is done with the side bolts, and shims, and also the two top bolts, and shims if you have to twist. Just remember, a .001 shim will go a long way.

So, if the sides are done, now you bring the top in, at 11:00, and 1:00 , the goal is 4 points that read less then .004, plus, or minus.

The magnets have to be level, the crank flange should be level. Use a dial indicator, to get true readings.

If after 4 points are made the same, or some are a little higher, you can remove the high amount with a coarse file, and a good shop vac.

We have had to do this with every one in 55 years, and that was a lot.

Herm.
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Mark Gregush
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Re: Magneto coil ring material..........?

Post by Mark Gregush » Fri Mar 29, 2019 1:35 am

I have done some tweaking on mine with a shot-peen mallet. That is all I am going to say, except it was suggested by a person that have been around T's for more then a while.
I know the voices aren't real but damn they have some good ideas! :roll:

1921 Huckster
1925 Cut down pickup


Topic author
George Andreasen
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Re: Magneto coil ring material..........?

Post by George Andreasen » Sat Mar 30, 2019 11:13 am

Herm, thanks for the advice and tutorial. I'll follow it.

About the bending question.........I actually tried it yesterday by clamping the ring to my big Royersford drill press. This press is the old "camel back", flat belt style and weighs at least 700 pounds, so it made a good work table. I clamped it across the 9 o'clock/3 o'clock positions using t-slot clamps and NOTHING through the mounting tabs as I wanted any strain placed on the frame alone. A 1 1/2 ton hydraulic jack was placed on the floor and a stout piece of oak 2 x 2 run from the jack to the edge of the ring.

Long story short, I DID get it to bend. The difference in height was right around .020" and I managed to reduce it to .010", so now I have a much better chance of getting my correct magnet clearance. It took three attempts, the first gaining .005", then I changed my push position to the thicker part of the frame instead of the thinner outside edge. I pushed the edge up over .120" AND LET IT SET for about 45 minutes, then released the pressure. My dial indicator showed the .010" gain, and that's where I stopped. Cast iron WILL bend, but it's not for the faint of heart!

When I bolted the ring back on the block and used a test bar at all positions, it was much more uniform with the bottom two poles being farther down than the top two by .010". Close enough. My replacement shims should be here today and I'll follow Herm's instructions.

By the way, I was flipping through Murry Fahnstock's book "The Model T Owner" and found something interesting in the magneto section. Murray states that new Ford cars were set up with the mag clearance at .020" (measured at the top). Every other source recommends .025" to .030". If his statement is correct it should increase the power somewhat.

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